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Running in hot weather: top tips and FAQs

Richard McVey
Senior Health Adviser at Bupa UK
12 August 2021

What happens to your body when you run in hot weather? Is running in the heat even good for you? Here I take a look at some of the most popular questions about summer running, so you can enjoy your run and stay safe.

Is it ok to run in hot weather?

Running in hot weather can feel more difficult, and without the right knowledge and preparation, it can even be harmful. When you run:

  • your muscles produce heat, which raises your body temperature
  • your heart rate increases to deliver blood flow to your skin’s surface to get rid of excess heat
  • you sweat to cool yourself down

In the heat, your body has to work even harder to do this. So make sure you plan your route and time, drink enough water and are sensible. Exercising outside does have benefits. It can be good for your mental health, give you a top up of vitamin D and if you can run in nature, all the better.

Can running in the heat make you sick?

Yes, running in the heat can make you feel unwell.

You may develop heat exhaustion which can make you feel dizzy, sick, weak and dehydrated. If you have these symptoms, rest, get into a cool place, drink plenty of water and lie down. Seek medical help if your symptoms don’t improve.

If you get too hot and your body can’t cool itself down, you could be at risk of getting heatstroke which a serious condition. Symptoms of heatstroke include confusion, clumsiness, blurred vision, dizziness, headache and rapid pulse. If you recognise these symptoms in yourself or somebody else, phone for an ambulance and cool yourself or the person down. One way of doing this is by getting into a cold-water bath.

How hot is too hot for running?

Different people adapt and respond to heat differently. If you’re very fit then you may be able to cope with the heat better than if you’re not used to exercising. Hot weather in general can be a risk to certain people, such as the elderly, young children, and those who have an underlying health condition.

The higher the outdoor temperature and humidity, the higher the risk of heat related illness and injury.

The American College of Sports Medicine advises that when the temperature is higher than 26.6 degrees C and the humidity is 75 per cent or over, then it may be better to exercise inside instead. You could run on a treadmill at the gym, for example.

What should I wear when running in hot weather?

Comfort is key when you’re running in the sunny weather; as is sun protection. Wear long sleeve tops to protect your arms, and choose loose-fitted, breathable (moisture wicking) fabrics. Many retailers now produce workout clothing using light materials designed to keep you cooler and drier.

Also look out for UPF on the label – this stands for UV Protection Factor. A shirt that has a UPF of 50 for example, only lets two per cent of the sun’s UV radiation reach your skin. A white t-shirt only has a UPF of three.

Don’t forget your accessories either; sunglasses and a hat or visor are just as important for extra protection.

Here are my top tips to help make your summer runs safe and enjoyable.

1. Stay hydrated

When it’s hot, your body sweats to try and evaporate heat and cool you down. You lose electrolytes such as sodium and potassium through sweating, which then need to be topped up. This means it’s really important to be hydrated.

Make sure you’re drinking enough water throughout the day, little and often, rather than just having lots before you run. Drink water before, during and after your run. Drink cool water if possible. Listen to your body; if you still feel thirsty, drink some more. Feeling thirsty means your body is showing signs of needing more fluid.

You might want to invest in a handheld runners water bottle, a water vest or running belt so you can take a drink with you. Alternatively, see if you can plan a route where you pass a few public water fountains on the way.

Keep an eye on your hydration status by checking your pee. It should be a pale straw-like colour.

If you’re running for longer than an hour, you may want to hydrate with a sports drink. The carbohydrates in sports drinks can replenish your glycogen (sugar) levels, and the electrolytes in these drinks help to speed up rehydration.

Image showing hydration level by urine colour

2. Use plenty of sunscreen

The sun’s ultraviolet (UV) rays can be damaging to your skin. So it’s important to make sure you use a good sunscreen with an SPF (Sun Protection Factor) of 30 or more, and a star rating of 4 or 5 to protect yourself. Choose a water-resistant sunscreen where possible. Your skin can become damaged or burnt even on cloudy days, so it’s always best to apply plenty of sunscreen before you head outside.

Remember to apply it everywhere that your skin is exposed. Some of the easily missed spots include your lips, the tops of your ears and the back of your neck.

3. Plan and time your runs appropriately

If you’re new to running, it’s probably best that you don’t choose a very hot day to do your first run.

The sun tends to be strongest between the hours of 11am and 3pm, so in general it’s better for all runners to try to avoid running between these hours. If you’re an early bird, a morning run could work for you. Not only will it be less hot, but it could also set you up for the rest of the day.

If you don’t have time in the morning, a cool evening run can be a good way to wind down at the end of the day. If you’re still finding it hard to avoid the sun, look for shaded areas wherever possible.

Be flexible with your routine – you might need to shorten the length of your run, go a bit slower, change your route, or even do a different activity altogether indoors.

4. Think about your diet

Eating well is important when taking part in any type of exercise. Getting the right food into your body will help to fuel your run and aid recovery afterwards. So if you find running in the heat impacts your performance, getting the right nutrition (PDF 1.23 MB) means there’s one less thing for you to worry about.

Think about nutrition before, during and after your run. Click on the image below to open the PDF (PDF 0.35 MB, opens in a new window).

Pre-exercise meal ideas


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Richard McVey
Richard McVey
Senior Health Adviser at Bupa UK

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